The interfacial reaction of Ni with relaxed Si1-xGex (x=0.2,0.3) films in the low temperature range, viz., 300–500 °C, has been investigated and compared with that of Ni with Si (i.e., x=0). Ni2(Si1-xGex) and Ni3(Si1-xGex)2 were observed at 300 °C whereas a uniform film of Ni(Si1-xGex) was formed at 400 °C for both Si0.8Ge0.2 and Si0.7Ge0.3 substrates. At 500 °C, a mixed layer consisting of Ni(Si1-yGey) and Si1-zGez was formed with a relation of z≫x≫y. Sheet resistance measurement results show that the silicided film attains its lowest value at an annealing temperature of 400 °C. The approximate values of the resistivity of the corresponding uniform Ni(Si1-xGex) (x=0.2, 0.3) derived from the transmission electron microscope and sheet resistance results are 19 and 23 μΩ cm, respectively. © 2002 American Institute of Physics.